Russian warships and naval assets have become a familiar sight for boat-spotters on the Bosphorus strait that runs through Istanbul and forms part of the boundary between Europe and Asia, a reminder for Turkey of Russia's presence in the Middle East, journalist Laura Pitel wrote on Sunday.

Pitel spoke to a group of amateur ship enthusiasts in Istanbul, who observe and photograph the vessels that pass through the strait.

"Here, you can be in Starbucks with an espresso and a ship is literally 250 metres away," one of them told her, explaining that they are easy to photograph because of the sharp bends and strong currents in the channel.

"There’s no other place on earth where you can capture them so well."

"Already this year, Russian warships have made almost four dozen trips up and down the strait. They include the hulking Moskva, a guided missile cruiser that is the flagship of the Russian Black Sea Fleet and provides air cover for Moscow’s deployment in Syria. It sports a red star on each side, and huge silver missiles that glint on deck in the sun," Pitel wrote.

"Kremlin-watchers say that, whether Turkey likes it or not, Russia is back in the Middle East. And its route runs right through Istanbul," she concludes.

The 1936 Montreux Convention on the Regime of the Straits regulates transit and navigation in the Straits of the Dardanelles, the Sea of Marmora and the Bosphorus.

The Convention gives merchant vessels complete freedom of passage through the Straits, while vessels of war are subject to some restrictions which make a differentiation between Black Sea and non-Black Sea countries.